Device for composing an infrared image

ABSTRACT

The invention relates to a device for composing an infrared image, which device is provided with a rotating body for scanning the infrared object to be imaged, and for recomposing the visible image. The rotating body comprises a disc with at least five abutting, outwardly reflecting roof-edge mirrors, regularly provided on the periphery of the disc.

uuucu )JlalU De Jong DEVICE FOR COMPOSING AN INFRARED IMAGE Inventor:Arie N. De Jong, Pijnacker,

Netherlands Assignee: Nederlandse Organisatie voor ToegepastNatwurwetenschappelijk Onderzoeh ten behoeve van de Rijksverdehiging,The Hague, Netherlands Filed: June 4, 1971 Appl. No.: 150,213

Related US. Application Data Continuation of Ser. No. 849,411, Aug. 12,1969, abandoned.

Foreign Application Priority Data Sept. 19, 1968 Netherlands 6813387 US.Cl. 250/347, 350/7 Int. Cl. G0lt 1/16 Field of Search 250/83.3 H, 83.3HP,

,[11] 3,775,619 i451 Nov. 27, 1973 [56] References Cited UNITED STATESPATENTS 3,460,892 8/1969 Dolin 350/7 X 3,508,051 4/1970 Nichols etal.... 250/83.3 H X 3,448,284 6/1969 Friesecke 250/234 3,647,956 3/1972Buck et al 350/7 X Primary Examiner-James W. Lawrence AssistantExaminerDavis L. Willis Attorney-Watson, Cole, Grindle & Watson [57]ABSTRACT The invention relates to a device for composing an infraredimage, which device is provided with a rotating body for scanning theinfrared object to be imaged, and for recomposing the visible image. Therotating body comprises a disc with at least five abutting, outwardlyreflecting roof-edge mirrors, regularly provided on the periphery of thedisc.

5 Claims, 3 Drawing Figures 0R mesa/s47 PATENIED 3,775,619

sum 1 or 2 FIG.1

DEVICE FOR COMPOSING AN'INFRARED'IMAGE This application is acontinuation of Ser. No. 849,41 1 filed Aug. 12, 1969 andnow abandoned.

The invention relates to a device for composinganq infraredimageprovided with'a rotating reflecting body for scanning the object line byline, a detector placed near that body and a reproduction systemsynchronized with the scanning movement. Such a device is known in theart as an infrared camera. In such infrared cameras a germanium cube isused as the means for effecting the scanning motion. During the scanningmotion the germanium cube turns around a shaft, going through the centreof two opposite planes of the-cube. A lens is disposed in the path ofthe rays-ahead of the cube which throws an image onthe heat detectorbehind the cube. By rotatingthe cube the image on the detector is movedalong a line, that is, at a motionless image on the detector, a line isscanned in.the field of vision of the camera.

Such prior art device is not without drawbacks. For

instance rigorous precautions must be taken to prevent variableradiation reflections. Such reflections are inter alia a result fromdiffusion of the light beamwhen it passes through the rotating cube.These reflections disturb the image on the detector. Also, such a devicedoes not present a simple solution for synchronizing the reproductionsystem with the scanning motion. It is therefore the object of thepresent invention to avoid these drawbacks. Accordingly the invention ischaracterized in that the body or means for effecting the scanningmotion comprises a disc with at least five abutting outwardly reflectingroof-edge-mirrors, regularly provided on the periphery of the disc. Adetector, imaged on the cylinder periphery through the cams of the roofsof the roof-edge-mirrors, with a sawtooth motion scans a line, theradiation being reflected against two mirroring planes being at rightangles. Whenever a cam of a roof-edge-mirror of the rotating body passesthe image of the detector, the scanning jumps back to the beginning ofthe line to be scanned which itself is scanned between two cams. Byapplication of the body it is possible to image more than one radiationdetector on the cylinder periphery through the cams of the roofs of theroof-edge-mirrors with the aid of a lens system or mirror system. Owingto this, it is possible to scan simultaneously as many lines in thefield of vision of the device as there are detectors. A simpleconstruction is obtained if the mechanical shaft of the disc makes anangle not equal to ninety degrees with the optical axis of the imagingsystem of the radiation detectors. lfwith the aid of a lens system or amirror system, as many crater lamps as detectors are imaged on thecylinder periphery through the cams of the roofs of the roof-edgemirror,then a simple and reliable mechanical synchronisation is realisedbetween systems of perception and reproduction. To obtain a simplestructure the mechanical shaft of the disc should preferably be providedat an angle not equal to ninety degrees with the optical axis of theimaging system of the crafter lamps. In an embodiment of the inventionthe imaging systems of the detectors and the crater lamps are mounted toa yoke movable with respect to the disc, the yoke being movable in aplane through the axis of the disc, and means being present to allowthat movement to operate with a sawtooth motion.

The invention will be further explained with reference to the drawingwherein:

FIG. 1 shows in an upper view a body according .to the invention witheight roof-edge-mirrors and a detector that is imaged on the cam of aroof of a roof-edge mirror;

FIG. 2 shows in a side-view a body according to FIG. 1 with threedetectors for scanning three parallel lines simultaneously and threecrater lamps of the reproduction system which are synchronized with thedetectors; and

FIG. 3 shows a schematic diagram of an embodiment of an infraredfield-glass according'to the invention.

In the figures like numbers refer to like elements.

In FIG. 1 disc 1 is provided with eight roof-edgemirrors 2 to 9rotatable in the direction of arrow 11 around shaft 10 drawn in an upperview. A detector D is imaged by lens L, on the cylinder peripherythrough cams 12to l9of mirrors 2 to 9. Image D just before cam 12 givesa virtual image D,,,. I

By rotating disc 1 in the direction of arrow 11 so that image D comesright across cam 12, a virtual image D arises. If disc 1 is rotatedfarther so'that image D is just before cam 13 then, during this movementof disc 1, the virtual image D has covered path s from D to D,,,.Consequently virtual image D, jumps from D to D g when a cam 12 to 19moves along D and virtual image D moves across path s from D back to Dwhen disc 1 moves across a sector before two earns 12 to l9along Dlnversely, an object in the field of vision ofroof-edge-mirrors 12 to 19indicated by angle a in FIGJ will be scanned with a sawtooth motion by apoint-shaped detector D through a line. If, thereafter, the detector ismoved slowly and also with a sawtooth motion parallel to shaft 10 in aplane through shaft 10 then the object is scanned by a number ofparallel lines in a direction perpendicular to that for thelinescanning.

In FIG.2 detectors D, to D, are imaged on rib 12 of body 1 via lens I.,.The optical axis of the imaging system makes an angle B with mechanicalshaft 10 of body 1. In order to obtain a correct synchronisation, craterlamps K, to K, must be in the same position with re spect to body 1 asdetectors D, to D for this purpose these crater lamps are presented onrib 12 of body 1 via lens L The optical axis of the reproduction systemalso makes an angle [3 with mechanical shaft 10 of disc 1. Detectors D,to D, modulate in intensity crater lamps K, to K, via amplifiers V, toV,,. By application of a number of detectors D, to D, a correspondingnumber of amplifiers V, to V and an equal number of crater lamps K, to Ka number of lines of an object to be scanned can be reproducedsimultaneously or all lines required for scanning an object at once, canbe reproduced. In the latter case it is not necessary to shift detectorsD, to D and crater lamps K, to K in a plane through shaft 10 andconsequently the means for scanning in a direction perpendicular to theline-scanning fall off.

FIG.3 shows an infrared viewer with 25 images a second. Shaft 10 of body1 is driven by motor 20. A programming disc 22 connected to body 1controls yoke 23 with a sawtooth motion via a mechanical coupling 21i.e. repeats successively slowly and uniformly in arrow direction a andfast and uniformly in arrow direction b To yoke 23 are connected mirrors25 to 28. An infrared beam B converged by lens 29 falls on body 1 viamirror 24. Body 1 reflects the beam to detector D via mirrors 25 and 26and lens L,. A crater lamp K projects its light to body 1 via lens L andmirrors 27 and 28. Body 1 reflects the light via mirrors 30 to 35 andlens 36 to 38. The beam that can be caught by eye 39 of the observeremerges from ocular lens 38. For the electric synchronisation craterlamp K is connected to detector D via an amplifier V. The intensity oflamp K thereby follows for visible light the lighting of detector D forinfrared light.

I claim:

1. A device for composing an infrared image profive mirrors, andwherein, with the aid of an optical system, at least one radiationdetector and at least one crater lamp is imaged on the cylinderperiphery through the cams of the roofs of the roof-edge mirrors.

-2.-A device according to claim 1, wherein with the aid of an opticalsystem at least one radiation detector is imaged on the cylinderperiphery through the cams of the roofs of the roof-edge mirrors.

3. A device according to claim 1 wherein a mechanical shaft of the discmakes an angle other than with the optical axes of the imaging systemsof the crater lamps.

4. A device according to claim 1 wherein the imaging systems of thedetectors and the crater lamps are mounted to a yoke movable withrespect to the disc.

5. A device according to claim 4, wherein the yoke can move in a planethrough the shaft of the disc and wherein means are provided forallowing that movement to proceed with a sawtooth motion.

1. A device for composing an infrared image provided with a rotatingreflecting body for scanning an object line by line, a detector placednear that body and a reproduction system synchronised with the scanningmovement, wherein the body comprises a disc with at least five abuttingoutwardly reflecting roof-edge mirrors, regularly provided on theperiphery of the disc, wherein the basic angles of the roof-edge mirrorsare chosen such that the reflecting surfaces of two mirrors adjacent oneanother are at right angles, the apex angle of each said mirrortherefore being determined by the formula: 90* - (360*/n) in which nrepresents at least five mirrors, and wherein, with the aid of anoptical system, at least one radiation detector and at least one craterlamp is imaged on the cylinder periphery through the cams of the roofsof the roof-edge mirrors.
 2. A device according to claim 1, wherein withthe aid of an optical system at least one radiation detector is imagedon the cylinder periphery through the cams of the roofs of the roof-edgemirrors.
 3. A device according to claim 1 wherein a mechanical shaft ofthe disc makes an angle other than 90* with the optical axes of theimaging systems of the crater lamps.
 4. A device according to claim 1wherein the imaging systems of the detectors and the crater lamps aremounted to a yoke movable with respect to the disc.
 5. A deviceaccording to claim 4, wherein the yoke can move in a plane through theshaft of the disc and wherein means are provided for allowing thatmovement to proceed with a sawtooth motion.